"Drug holiday" will change the standard of care, reduce side effects for men with recurring prostate cancer

TORONTO, Sept. 5, 2012 /CNW/ - Results of a clinical trial published
today in The New England Journal of Medicine shows that men with prostate cancer who are treated with intermittent
courses (known as a drug holiday) of androgen-suppressing therapy will
live as long as those receiving continuous therapy.

The trial was led by the NCIC Clinical Trials Group, which is funded by
the Canadian Cancer Society. It found that not only do the men live as
long, they may also experience greater quality of life with fewer
uncomfortable side effects from continuous exposure to
androgen-suppressing therapy. Side effects include hot flashes, sexual
impotence, growth of breast tissue, insomnia, weight gain, worsening of
diabetes, loss of muscle mass and osteoporosis. These side effects are
due to the lack of testosterone produced by the drugs. Patients
receiving intermittent courses of the androgen-suppressing drug
reported reduced hot flashes, urinary problems and fatigue, and an
increase in sexual desire.

The findings also have significant economic implications: patients on
the intermittent therapy used only one-third the amount of the drug,
which is very costly.

"We have known since the mid-1990's that androgen-suppressive therapy
could be used in an interrupted fashion, but we didn't know until now
that men were not sacrificing length of life in the hopes of having a
better quality of life," says Dr Juanita Crook, principal investigator
and radiation oncologist with the BC Cancer Agency. "The results of
this trial will change the standard of care." Dr Crook co-led the study
with Dr Laurence Klotz, a clinical urologist at Toronto's Sunnybrook
Health Sciences Centre.

Since the growth of prostate cancer depends on the male hormone
testosterone, one of the commonly used treatments is a form of hormone
therapy to lower testosterone (androgen) levels. Men who took part in
this clinical trial had initially undergone radiation treatment for
their prostate cancer, in some cases preceded by surgery, but
subsequently experienced elevated PSA levels (prostate-specific
antigen) indicating that their cancer had returned. A total of 1386 men
participated in the trial which recruited patients from 1999 until
2005. Most were from Canada; others were from the US and the UK.

The standard treatment until now has been to use continuous therapy but
this is expected to change as a result of these findings. "The findings
of this research study will change the way men suffering a recurrence
of prostate cancer are treated, and improve their overall quality of
life, says Dr Christine Williams, VP of Research, Canadian Cancer
Society.

Patients in the trial were randomized into 2 different groups: the
control group of men received slow-release injections of an LHRH
blocker (luteinizing-hormone-releasing hormone). Injections of the drug
were given every 3 months and lasted for 3 months to provide continuous
suppression of testosterone. The experimental group received the same
drug but in treatment cycles that were 8 months long, interrupted for
extended "drug holidays" lasting several months to years. These men
were monitored every 2 months using the PSA test. If a patient's PSA
levels rose while off treatment, he would then resume treatment with
the LHRH blocker for another 8-month cycle until his PSA levels dropped
again, and so on.

The follow-up period of the trial was stopped early because a planned
mid-trial analysis, reviewed by an independent data and safety
monitoring committee, unequivocally demonstrated no difference in
survival outcome between the two groups of men.

About the NCIC Clinical Trials Group
The NCIC Clinical Trials Group is a national research program of and is
funded by the Canadian Cancer Society. Additional support for the trial
was provided by the United States National Cancer Institute (Grant
#CA077202) and Sanofi-Aventis.

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